The invention relates to electric lamps and particularly to electric lamps with integral reflectors. More particularly the invention is concerned with an electric lamp with an integral reflector and a light shield.
Reflector lamps are commonly coated to reflect light forward. It can be difficult to adequately coat the neck region of the reflector to block light from exiting incorrectly through the neck, or to adequately shield the neck region from heat. As a result, light can shine through the neck, which may be unaesthetic or even unacceptable in display lighting applications. Similarly the light, including infrared heat, may shine into the socket region causing an undesirable or unacceptable heating of the lamp base, and socket region. To prevent such transmission, the neck regions of lamps have been coated with reflective material. This is reasonably functional in larger volume lamps where the neck is sufficiently open to receive the metal vapor. In smaller lamps good metallization in the small neck region is difficult to achieve. In dichriocally coated lamps, the multiple coatings are even more difficult to apply accurately. An alternative blocking method is to insert a metal shield in the neck region. Metal shields work well in larger lamps. Metal shields do have the problem of darkening with repeated heating. For example, nickel, steel and stainless steel shields, commonly darken. This darkening reduces the amount of reflected light, and enhances heat absorption and therefore retransmission of heat into the neck and socket region. The lost light is one detriment. The darkening can also be unaesthetic in display lighting where the original high quality lamp color (dichrioc or silvered) is expected as part of the jeweled display pattern. Aged, and variably discolored lamps are then felt to detract from the display. Heating the socket and seal regions can have other problems. Metal shields also provide conduction paths that at times can short circuit the lamp leads. This is a particularly difficult aspect of shielding small volume lamps were the leads are close together, and there is little surrounding volume to contain the metal shield. There is then a need for a small volume reflector lamp that does not project light into or through the base region, does not discolor and does not short circuit the lamp leads.
A reflector lamp may be made with a glass shell having an interior surface extending from a reflector region that defines a reflector cavity to a neck region that defines a neck cavity. Positioned in the reflector and neck cavity regions is a light source offset from the interior shell surface and electrically connected by a first lead and a second lead extending respectively through the neck cavity region to an exterior of the shell. The lamp additionally includes an opaque ceramic shield positioned in the neck cavity intermediate the light source and the neck region having a first surface facing the light source and a second surface facing the neck region. The ceramic shield then blocks light into the neck region while thermally and electrically insulating the lamp and the associated lamp leads.